This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The live attenuated measles vaccine has an outstanding efficiency and safety record and induces enduring immunity. We hypothesize that a currently used measles virus (MV) vaccine strain is an ideal platform for the development of pediatric vaccines eliciting immunity against other pathogens. We will test two propositions of this hypothesis: first that vectored MVs can protect against infection with another pathogen. Second, that they can elicit a strong immune response against other human pathogens whilst maintaining vaccine function against measles. Recombinant MV expressing the surface antigen of the hepatitis B virus at different levels will be used to define the expression strategy most effective in inducing a strong humoral immune response. Those viruses inducing the strongest immune response against hepatitis B in genetically modified mice will be inoculated into juvenile macaques. Their efficacy in protecting these primates against wild type measles infection and in inducing an immune response against the additional pathogen will be measured.